Neonatal mortality risk for the eighties: the importance of birth weight/gestational age groups.

Since 1976 a computerized data base has been used to store information on babies admitted to two intensive care nurseries serving the Vermont/New Hampshire region. The data base now allows reporting "neonatal" mortality by birth weight/gestational age (BW/GA) groupings for 1976--1979. For all BW/GA groups, except the most immature infants, there has been marked improvement compared to data gathered in the sixties (ie, mortality has decreased). These data are probably applicable to most other centers providing neonatal intensive care. The use of BW/GA categories provides the most reliable way of objectively comparing statistics from one center to another. Differences between two centers were observed when birth weight specific rates were used, but were largely abolished by using BW/GA groups. Data gathered in this way will be increasingly important for comparisons between centers and across years and when evaluating the effectiveness of new therapeutic interventions.